Hi, I am keep on reading frequency count using Timer and i need to store this frequency count in the DMA for every second (when interrupt trigger). what are functions write into DMA and read back from DMA

I am keep on reading frequency count using Timer and i need to store this frequency count in the DMA for every second (when interrupt trigger). what are functions write into DMA and read back from DMA when PLC requested.

 i am new to DMA if any sample code or suggestion it would be great ..!!